The present invention relates generally to weld assemblies for forming conductor to conductor welded connections and more particularly to conversion plugs for weld molds which allow a single weld mold design to be used for multiple applications.
Exothermic weld assemblies are used to connect two or more conductors, such as electrical wires to grounding rods or reinforcing rods and the like. Exothermic welds have long been recognized as providing an excellent electrical quality connection between two or more conductors. Exothermic welds provide low resistance, high ampacity and long-lasting, reliable grounding connections.
Conventional exothermic weld assemblies typically have a crucible in a top section in fluid communication with a mold section therebelow through a tap hole extending from the bottom of the crucible. The crucible includes a chamber for holding a quantity of exothermic material. The mold section includes a weld chamber and a plurality of guide holes connecting the weld chamber and the exterior of the mold. The ends of the conductors that are being welded together are inserted into the weld chamber through these guide holes. The weld molds (also referred to as welding molds) are made with various configurations based on the number and size of the conductors that are being connected. Two of the most commonly used configurations are the xe2x80x9cwire to rodxe2x80x9d and xe2x80x9cwire to wirexe2x80x9d designs. In the xe2x80x9cwire to rodxe2x80x9d design, the rod usually enters the weld chamber from the bottom and one or more wires enter the weld chambers through the side walls.
The crucible and mold may be designed as a single unit or two individual units and each unit may be disposable or reusable. The exothermic material in the crucible is ignited to produce a chemical reaction that is completed typically in seconds and produces a molten metal. The liquid metal flows from the crucible section into the weld chamber of the mold section where it envelops the ends of the conductors causing them to melt and thereby weld together.
The ends of the conductors to be welded are inserted into the weld chamber via guide holes, which allow the weld chamber to communicate with the outside of the weld assembly. Examples of such exothermic weld molds are disclosed in U.S. Pat. No. 3,020,608 to Gelfand and U.S. Pat. No. 5,715,886 to Fuchs, which are incorporated herein by reference. Typically, these guide holes are pre-formed in the mold in a variety of different configurations to accommodate the number of conductors which are being connected, as well as their size and orientation. Many weld mold designs can be modified for specific applications by drilling additional guide holes through the mold into the weld chamber.
Conventional weld molds are disposable, single use units that are generally cylindrically shaped structures with a curved outer surface. The weld molds are available with limited variations in the number and location of the guide holes. Some weld molds are constructed so that additional guide holes can be drilled depending upon the application and the number of conductors to be joined. However, one of the problems with conventional weld mold assemblies is that there is no convenient way to modify an assembly which has more guide holes than required for an application. Accordingly, to provide for the different applications that may arise, it is necessary to have many different weld mold assembly designs available with a variety of guide hole configurations. This requires a user to stock a large inventory of weld assemblies. Thus, conventional exothermic weld assemblies are less than satisfactory and there is a need for a weld mold assembly that can be configured for use in a variety of different applications.
Accordingly, it would be desirable to provide an exothermic weld assembly which can be easily adapted to a variety of different configurations without having to drill additional holes.
The present invention relates to a weld mold assembly which includes a crucible section for exothermically reacting weld material to form a molten metal; a weld mold including a weld chamber with an opening for receiving the molten metal and in communication with the crucible section; and a conversion plug sealably inserted into at least one of the guide holes. The guide holes have a weld chamber end and an exterior end and can receive ground rods and/or wires. The conversion plug can be cylindrical or tapered to provide a frustoconical shape. The weld mold also includes a plurality of guide holes extending from the weld chamber to the exterior of the weld. In one embodiment, the weld mold includes a guide hole for receiving a ground rod and a plurality of guide holes for receiving wires. The crucible section, which is used for exothermically reacting weld material to form a molten metal, is in communication with the opening in the weld chamber through a tap hole. In another embodiment of the present invention, the crucible section can be separated from the weld chamber so that the crucible section can be reused. A nozzle separably connects the crucible section and the weld chamber so that the tap hole is in communication with the opening in the mold chamber.
The weld mold is constructed from a refractory frangible material and can have a plurality of flat exterior surfaces. The conversion plug is fabricated from a ceramic, graphite or a refractory frangible material. The conversion plug is inserted into the guide hole from the weld chamber end or from the exterior end. A wire or sheet metal clip can be used to hold the conversion plug in place. The weld mold assembly can be designed so that the weld mold assembly is disposable or reusable.
In one embodiment, the conversion plug includes a ceramic or graphite cylindrical body having a first end and a second end, wherein the distance between the ends is greater than the diameter of the cylindrical body. In a preferred embodiment, the cylindrical body is tapered toward the second end. In another embodiment, the conversion plug includes a base connected to the cylindrical body at the first end.